dispose, #71

doc/implementation-notes.md

@@ -66,7 +66,7 @@ and sim-specific) to the browser console.
 ### Memory Management
 
 * **Dynamic allocation:** Most objects in this sim are allocated at startup, and exist for the lifetime of the
-  simulation. The exception is `Electron`, which are dynamically created when a coil is modified (see number of loops 
+  simulation. The exception is `Electron`, dynamically created when a coil is modified (see number of loops 
   and loop area). Electrons do not need to be stateful, and the number of Electrons is derived.
 
 * **Listeners**: Unless otherwise noted in the code, all uses of `link`, `addListener`, etc. do NOT need a

js/common/model/Coil.ts

@@ -193,12 +193,20 @@ export default class Coil extends PhetioObject {
       ( numberOfLoops, loopRadius, frontColor, middleColor, backColor ) =>
         Coil.createCoilSegments( numberOfLoops, loopRadius, this.wireWidth, this.loopSpacing, frontColor, middleColor, backColor ) );
 
+    // When a new set of CoilSegments is created, dispose of the old set.
+    this.coilSegmentsProperty.lazyLink( ( newCoilSegments, oldCoilSegments ) =>
+      oldCoilSegments.forEach( coilSegment => coilSegment.dispose() ) );
+
     this.electronsProperty = new DerivedProperty( [ this.coilSegmentsProperty ],
       coilSegments => this.createElectrons( coilSegments ), {
         // Erroneously identifies options to new Electron in createElectrons as dependencies.
         strictAxonDependencies: false
       } );
 
+    // When a new set of Electrons is created, dispose of the old set.
+    this.electronsProperty.lazyLink( ( newElectrons, oldElectrons ) =>
+      oldElectrons.forEach( electron => electron.dispose() ) );
+
     this.electronsMovedEmitter = new Emitter();
   }
 

js/common/model/CoilSegment.ts

@@ -69,6 +69,10 @@ export default class CoilSegment {
   public evaluate( t: number, returnVector?: Vector2 ): Vector2 {
     return this.curve.evaluate( t, returnVector );
   }
+
+  public dispose(): void {
+    // Nothing to do currently. But this class is allocated dynamically, so keep this method as a bit of defensive programming.
+  }
 }
 
 faradaysElectromagneticLab.register( 'CoilSegment', CoilSegment );

js/common/model/Electron.ts

@@ -97,6 +97,10 @@ export default class Electron {
     this.speedScaleProperty = options.speedScaleProperty;
   }
 
+  public dispose(): void {
+    // Nothing to do currently. But this class is allocated dynamically, so keep this method as a bit of defensive programming.
+  }
+
   /**
    * Gets the layer that this electron currently occupies.
    */

js/common/model/QuadraticBezierSpline.ts

@@ -12,6 +12,7 @@
 import faradaysElectromagneticLab from '../../faradaysElectromagneticLab.js';
 import Vector2 from '../../../../dot/js/Vector2.js';
 import { Shape } from '../../../../kite/js/imports.js';
+import Disposable from '../../../../axon/js/Disposable.js';
 
 
 export default class QuadraticBezierSpline {
@@ -59,6 +60,10 @@ export default class QuadraticBezierSpline {
       .moveToPoint( this.startPoint )
       .quadraticCurveToPoint( this.controlPoint, this.endPoint );
   }
+
+  public dispose(): void {
+    Disposable.assertNotDisposable();
+  }
 }
 
 faradaysElectromagneticLab.register( 'QuadraticBezierSpline', QuadraticBezierSpline );

js/common/view/ElectronsNode.ts

@@ -138,7 +138,7 @@ class ElectronSpriteInstance extends SpriteInstance {
   }
 
   public dispose(): void {
-    // Nothing to do currently. But keep this method as a bit of defensive programming.
+    // Nothing to do currently. But this class is allocated dynamically, so keep this method as a bit of defensive programming.
   }
 
   /**

js/common/view/FieldNode.ts

@@ -166,7 +166,7 @@ class CompassNeedleSpriteInstance extends SpriteInstance {
   }
 
   public dispose(): void {
-    // Nothing to do currently. But keep this method as a bit of defensive programming for rebuild method.
+    // Nothing to do currently. But this class is allocated dynamically, so keep this method as a bit of defensive programming.
   }
 
   /**